This invention is in the field of biochemistry, pharmacology, and nutritional supplements, and relates to a new use for zeaxanthin, a carotenoid found in plants such as spinach, kale, and corn.
Numerous efforts have been made to identify drugs or other biomolecules that can be orally ingested and that will safely accomplish either or both of the following: (i) cause a darkening of the color (also referred to as tint, tone, pigmentation, or similar terms) of the skin, in a manner that looks like a healthy and natural suntan, while reducing or eliminating the need to spend hours in direct sunlight or in front of ultraviolet lamps; and/or, (ii) reduce the risk of a sunburn, such as when the summer season is approaching, and when someone is planning a vacation, golf or fishing outing, a ski trip, or some other activity or travel that will likely result in substantially more sun exposure than a person has had over the preceding month or two.
If either of these effects could be provided, safely and effectively, by a compound that could be put in a bottle, the value and benefits would be very large, both for cosmetic and commercial reasons, and for medical reasons as well. It is well known that overexposure to direct sunlight causes and accelerates premature aging and wrinkling of skin. It has also been shown that if a person suffers several serious sunburns (especially when young), it will increase that person's risk of skin cancer (including melanoma, an extremely malignant and deadly cancer) later in life. In addition, because of ozone depletion in the upper atmosphere, both of these risks are likely to accelerate and become worse in the future, since the ozone layer plays a crucial role in reducing and controlling the amount of skin-damaging ultraviolet rays that reach the earth's surface.
In addition, it is also likely that if people could obtain a “pre-season suntan”, they might also get more exercise, and would be healthier as a result, since having an overly pale and “pasty” appearance tends to discourage people from getting involved in outdoor activities with other people.
It also is known that various types of drugs (such as quinoline antibiotics, as just one example) can create a condition of hypersensitivity to sunlight, which will increase the risk of sunburns and other skin problems. Accordingly, if someone is taking (or is planning to take) a therapeutic drug which will create that type of side effect, it would be highly useful if a second agent were available which could mitigate the skin-related or sun-related side effects of the therapeutic drug.
In addition, some people suffer from diseases or syndromes in which their skin is abnormally sensitive and vulnerable to sunburns, or to the formation of uneven or discolored patches (often called blotches or splotches) that go beyond the normal formation of freckles, or other types of discomfort or lesions, when people who suffer from these diseases or syndromes have their skin exposed to direct sunlight. One class of such diseases, which involve defects in the biosynthesis or metabolism of heme (the protein that complexes with iron to make hemoglobin), is generally referred to as porphyrias; this cluster of diseases is subdivided into at least a dozen named subclasses, such as “erythropoietic protoporphyria”, etc. Another class of diseases or syndromes which render some people abnormally vulnerable to skin damage by sun involves the trait of albinism, in which people have abnormally pale skin due to low quantities of melanin, the dark brown or black pigment that normally occurs in skin and various other tissues. It is anticipated that orally-ingested zeaxanthin as disclosed herein may be able to help mitigate at least some of these types of skin diseases or syndromes, as can be evaluated through routine trials on patients who suffer from any such disease or syndrome.
It should be noted that the term “skin” as used herein refers to epidermal layers (including surface layers, as well as near-surface layers that can be affected by sunburns), in any one or more areas of the body, head, or limbs (including areas of the scalp, etc). As will be recognized by anyone skilled in the art, the primary areas of concern are those areas that are or may be exposed to sunlight or other UV radiation, and if any significant level of additional protection to any one or more of those areas can be provided by zeaxanthin treatments disclosed herein, that is deemed to be a valuable result. As just one example, a golfer or fisherman (or anyone else) is likely to have his forearms, nose, forehead, and other areas exposed to sufficient sunlight, during the spring and early summer, to build up a sufficient tan in those areas to prevent any substantial burning, during normal activities. However, after a day at a beach, pool, lake, golf course, or other such area, that person may suffer a severe sunburn on his feet, or the tops of his ears (after a recent haircut), or some other area that is normally covered by clothing or hair, and those types of severe sunburns can cause both serious pain, as well as increased risks of skin cancer, premature aging, and other problems. Accordingly, the zeaxanthin treatments disclosed herein can be used to protect against such “limited area” burns or damage.
The term “skin” does not include epithelial surfaces, which are commonly referred to as mucous membranes, and which notably includes the lips (which occasionally suffer from sunburns that can be very painful due to the large numbers of nerve endings in and near the lips). None of the test subjects reported in the Examples suffered any sunburns on their lips, while taking zeaxanthin, and it is believed likely that zeaxanthin ingestion as disclosed herein can provide at least some level of increased protection against UV damage, for the lips and other epithelial surfaces. However, that likelihood has not yet been evaluated by any tests that focus specifically on epithelial surfaces.
At the current time, most efforts to create “suntan in a bottle” compounds that have a reached actual commercialization and public use involve lotions, creams, and similar “topical” agents that are applied directly to a surface of the skin. Examples of agents which are used in such lotions and other topical formulas include dihydroxyacetone, erythrulose, and tyrosine. Such topical formulations can be used in conjunction with “systemic” (i.e., orally-ingested) tanning agents, including the zeaxanthin-containing oral formulations disclosed herein. While the present invention is principally directed to oral dosages of zeaxanthin, as will be discussed below, it should be noted that zeaxanthin can also be added to a tanning lotion or other topical formulation, to achieve beneficial results.
The principal focus of this invention relates to orally-ingested formulations. Such orally-ingested formulations are referred to herein as “oral tanning” agents, compounds, products, or formulations. For convenience, they are also referred to herein simply as tanning agents (or compounds, formulations, etc.), with the understanding that the class of tanning agents being referred to herein are limited to agents that are designed and formulated to be orally ingested, unless a particular reference refers to a topical formulation such as a lotion. Since various lotions and other topical formulations are already commercially available for imparting a darker tint if applied directly to the skin, the primary value of the discovery disclosed herein appears to reside in its disclosure of a truly safe yet effective and potent agent that, when taken orally, can protect skin against sunburn and certain other types of skin problems, regardless of whether any lotions or other topical formulations are also used.
It also should be noted that the term “photoprotective” is frequently used to refer to agents that can protect against sunburn, create or enhance tans, etc. However, that term is not favored or used herein, since it is too broad and non-specific, and can include every type of formulation discussed herein, plus a wide range of other agents as well (including hats, sunglasses, conventional sunblocking and SPF-rated suntan lotions, and opaque ointments and creams). Many types of “photoprotective” agents are intended simply to block the harmful rays of the sun. By contrast, this invention discloses an oral agent that can treat the skin in a manner that will lead to a change in pigmentation and/or antioxidant concentration within and/or beneath the skin, in a manner which will render the skin better-prepared to deal with direct sunlight, thereby reducing the risk and/or severity of skin problems such as sunburns, premature wrinkling and aging, skin cancer, etc.
On the subject of orally-ingested tanning agents, it should be noted that various types of pills are sold with labels and advertisements suggesting that those pills may be able to help accelerate or promote tanning. However, the only such orally ingestible agent that actually works effectively for that purpose contains canthaxanthin, which has been declared illegal for tanning purposes because of a type of damage that was observed in the retina when high dosages were ingested (as discussed in more detail below). Other agents, such as tyrosine (an amino acid that is a precursor of melanin) are only marginally effective at best, and are generally dismissed as being ineffective, in reviews and analyses that are available on websites such as http://www.sunless.com/safe/tanningpillsdontwork.php However, it should be noted that research is being done on other agents, most notably including “melanocyte-stimulating hormone” (MSH) and various analogs or active fragments thereof, which are not currently available to the public, but which may become available someday.
Roughly 20 years ago, a class of compounds called “carotenoids” was recognized as having good potential as orally-ingested tanning agents, because of the biological roles and effects of carotenoids in nature. Very briefly, carotenoids are large organic molecules that have numerous double bonds between carbon atoms; the chemical structures of several important carotenoid molecules are shown in the enclosed FIG. 1.
The alternating pattern of double and single bonds shown in FIG. 1 is the conventional structure shown in drawings to represent carotenoids. However, because of the clustering of these double bonds, the electrons that surround the straight-chain portion of these carotenoids actually form a fluid-like and movable network that resembles the “resonating” or “electron cloud” structures of aromatic rings such as benzene. This “resonating” system of interacting electrons in a movable cloud allows carotenoids to absorb UV light very efficiently, without being destroyed. In a sense, this absorbing action is analogous to a boxing glove punching a foam rubber pillow, rather than a wooden board; because the pillow can flex, adapt, and adjust to the impact, it will not be broken, even by a blow that would easily break a wooden board. And, just as a pillow can absorb the force of a blow from a boxing glove, when a carotenoid molecule absorbs the energy of a UV photon, it prevents the UV photon from damaging other biomolecules (such as DNA or proteins).
On the subject of conjugation, it should be noted that zeaxanthin has a higher degree of conjugation than lutein. As shown in FIG. 1, the conjugated (and therefore resonant) electron structure of zeaxanthin extends into both of the end rings. That does not occur with lutein, which is non-symmetric, and which has a non-conjugated end ring.
On the subject of comparative structures, it also should be noted from FIG. 1 that zeaxanthin has a hydroxy group on each of its end rings, while 13-carotene does not have either of those two groups. As is well known to chemists, when hydroxy groups are added to an organic structure, they tend to make that structure more polar, and more soluble in water. Since the two hydroxy groups on zeaxanthin are positioned on its end rings, they tend to give zeaxanthin better “membrane-spanning” traits than i3-carotene (as well as certain other types of positioning and interacting traits, in aqueous and cellular systems).
It should also be kept in mind that after s-carotene is ingested, one of its predominant fates is to be cleaved in half, so that the two halves can be used to make Vitamin A and other retinoid molecules. That apparently does not happen with zeaxanthin. Therefore, ingested zeaxanthin appears to be capable of lasting and enduring, in a mammalian body, for substantially longer periods of time than 1-carotene.
Because of their extremely useful roles as UV absorbers, and also as anti-oxidants (as discussed below), carotenoids evolved over the eons to play very important roles in plant leaves, and in bacteria that must grow in direct and prolonged sunlight.
As indicated above, carotenoids are pigment molecules. Their colors are generally red, orange, or yellow, because those are the color ranges that remain and are reflected outwardly, when light in the blue and ultraviolet region of the spectrum is absorbed by the carotenoid molecules. When the leaves of trees or bushes turn red, orange, and yellow in the fall, those colors are due mainly to carotenoids, which become the dominant pigments in the leaves after chlorophyll production slows down because of cold weather, and after any chlorophyll that still remains in the leaves when cold weather arrives is gradually degraded.
In addition to being pigments that can absorb ultraviolet radiation, carotenoids also are potent anti-oxidant compounds. This means that they can “scavenge” or “quench” certain types of highly reactive and damaging molecules called “oxygen free radicals”. Oxygen free radicals are commonly created when a photon of UV light breaks apart a biological molecule that contains oxygen, in a manner that creates a single “unshared electron” on one surface of the oxygen atom. Because oxygen free radicals are highly unstable and reactive, they pose a serious danger of randomly attacking and damaging nearly any type of biological molecule or membrane. Therefore, the ability of carotenoid molecules to absorb and “quench” oxidative free radicals played a very important and useful contributory role in the evolution of carotenoid molecules as one of the primary natural defenses against UV damage in plants, and among bacteria that must be able to withstand direct sunlight for hours.
As mentioned above, by the early 1980's, carotenoids were recognized as being potentially useful as orally-ingested tanning agents, for two main reasons: (i) they are naturally-occurring pigments with the desired color ranges; and, (ii) their role in nature is to absorb UV rays, and protect cells against UV light damage.
Based on those facts, an orally-ingested tanning agent containing a particular carotenoid called canthaxanthin (also spelled as canthaxanthine) was developed and marketed in a number of countries, under the trademark OROBRONZE™. It was a successful product for a number of years; however, after people had been using it for years, it was declared to be unsafe, and it was withdrawn and pulled off the market, because of an unanticipated side effect which became apparent only after years of use. This unwanted and dangerous side effect became evident because canthaxanthin crystals were being formed and deposited in the retinas of people who had been taking OROBRONZE capsules. That unwanted and dangerous side effect is described in various medical articles, including McGuinness et al 1985, Lonn 1987, and White et al 1988.
After canthaxanthin was declared illegal as a suntanning agent because of the retinal crystal problem, interest turned to β-carotene as a potential orally-ingested tanning agent (see, e.g., Mathews-Roth 1986 for a review), and at least one product, called BETATENE™, is being sold for that purpose (e.g., Stahl et al 1998). However, ever after years of use as an oral sun-tanning agent, it is not at all clear whether it works for that purpose, and if so, whether any value it may offer is accompanied or outweighed by unwanted risks and adverse effects. For example, as stated in Biesalski et al 2001, “most clinical studies have failed to convincingly demonstrate its beneficial effects so far. . . . Recent studies on skin cells in culture have revealed that β-carotene acts not only as an antioxidant but also has unexpected prooxidant properties. At present, there is an ongoing debate on the protective or potentially harmful role of i3-carotene in human skin.”
That reference to “pro-oxidant” properties needs special attention, because it indicates an alarming risk. Instead of reducing the damaging effects of oxidative free radicals, it appears that under at least some conditions, β-carotene may aggravate and worsen the types of damage that oxidative free radicals inflict on cells and biomolecules. This same warning was also contained in Eichler et al 2002, which stated, “The amounts of carotenoid needed for optimal protection [in certain types of cell culture tests, which used human fibroblast cells] were divergent at 0.05, 0.40 and 0.30 nmol/mg protein for lycopene, β-carotene and lutein, respectively. Beyond the optimum levels, further increases of carotenoid levels in cells led to pro-oxidant effects.”
That warning signal raises serious questions, because it is impossible for people taking dietary supplements to know when they have reached, and when they have exceeded, the optimal or maximal levels that are safe, when cell culture conditions must be translated into practical advice concerning in vivo usage and dosages for humans. Accordingly, the warnings about β-carotene's “pro-oxidant” activity must be taken seriously, in view of the failure of β-carotene to offer any clear benefits with respect to preventing sunburns, in clinical trials on humans.
Along those same lines, it should also be noted β-carotene was recently discovered to pose a substantial health risk, relating to lung cancer and possibly other forms of cancer. In the mid to late 1990's, in three large and well-run multinational trials, it was discovered that daily ingestion of only 30 to 60 mg/day of β-carotene was enough to elevate the risk of lung cancer, among smokers, by factors approaching 30%. Those studies including the Beta Carotene and Retinal Efficacy Trial (CARET) done in the United States, and the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC), done in Finland; they are reviewed in articles such as Goodman 2000. The risk-increasing dosage levels of i3-carotene (30 to 60 mg/day) were only a small fraction of the recommended dosage levels of 180 mg/day, for people who were given i3-carotene to treat skin diseases (see Mathews-Roth 1993). Therefore, those lung cancer data raise very serious questions about whether β-carotene can be taken safely, at the types of very high dosages that may be capable of provoking a significant darkening of skin tint.
In comparing zeaxanthin to β-carotene as a potential orally-ingested tanning agent, two additional factors should be noted. First, zeaxanthin (as well as lutein, canthaxanthine, and various other carotenoids) are classified as “non-retinoid” compounds, whereas β-carotene is a retinoid compound. The distinction between those two classes is that retinoid compounds are cleaved into two segments, and those two smaller molecules become Vitamin A, or similar molecules (which are generally classified as retinoid compounds). By contrast, “non-retinoid” carotenoids are not cleaved in that manner (at least, not in substantial quantities), and are not converted into Vitamin A or other retinoid compounds.
A second major factor which distinguishes zeaxanthin from β-carotene, as a skin tanning agent, centers on the effective dosage levels. As mentioned above, when people were given β-carotene to treat skin diseases such as porphyria, effective dosage levels of 180 mg/day were required. By contrast, among people taking zeaxanthin, dosages of only about one-sixth to about one-third of those levels (in the range of 30 to 60 mg/day) were required to induce substantial darkening of skin tint. Lower required dosages can lead not just to cost savings, but also to substantially higher margins of safety, and other benefits.
Some recent patents indicated that there is still interest in developing orally-ingested tanning formulations. U.S. Pat. No. 6,254,898 (Bragaglia 2001) discloses a mixture of green tea extract, lutein, lipoic acid, and selenomethionine, for use as an oral tanning agent. One of those ingredients, lutein, is a carotenoid. As mentioned in that patent, most of the plant sources (such as marigold flowers, which are bright yellow or orange) which are used to obtain commercial quantities of lutein also contain trace amounts of zeaxanthin; therefore, the tanning mixtures patented by Bragaglia referred to “lutein (zeaxanthin)”.
U.S. Pat. No. 6,433,025 (Lorenz 2002) claimed the use of a different carotenoid, called astaxanthin, in orally-ingested tanning products. According to Lorenz, astaxanthin has roughly ten times the potency of other carotenoids (including castaxanthin, lutein, zeaxanthin, etc.) as an anti-oxidant protective agent.
Background Information on Zeaxanthin and Lutein
The subject invention focuses on zeaxanthin, a carotenoid which has been shown by the inventors herein to be useful as an orally-ingested tanning agent, when ingested at relatively high dosages in the range discussed below.
In the mid-1980's, it was discovered that zeaxanthin and lutein (their structures, which are very similar, are shown in FIG. 1) are the two carotenoids that are present in a small yellow-colored spot at the center of the human retina, called the macula.
Lutein can be obtained cheaply, in bulk, from marigold flowers, and it has been available for years. It is widely fed to chickens and to farm-raised salmon, since it helps create a darker and richer color to chicken skin, egg yolks, and salmon meat, which makes those pigmented products look fresher, healthier, and more appealing to purchasers and consumers. However, lutein tends to impart a yellow (rather than golden) tint to chickens and fish, when fed to them as a food additive. Therefore, lutein usually must be accompanied by at least one red-colored pigment, to allow the pigment mixture to impart a more desirable darker and richer golden tint to chickens and salmon.
Unlike lutein from marigolds, zeaxanthin has no simple and convenient plant source, and is present at only very tiny concentrations in natural foods. It also is very difficult to synthesize and purify. Therefore, zeaxanthin did not become commercially available to the public until 2002.
Because they are both known to be present in the human retina, and because they are both known to have UV-absorbing and anti-oxidant properties, lutein and zeaxanthin have recently begun to be advertised and sold as being potentially useful in helping treat or reduce the risk of a retinal disease called “macular degeneration”, which is a leading cause of blindness among the elderly. Under the “DSHEA” law (an acronym for the Dietary Supplement Health and Education Act, passed by Congress in 1994), those types of sales are allowed under a set of rules that apply to “dietary supplements” which contain ingredients that already exist in foods and are part of the normal human diet. Since lutein and zeaxanthin both exist in spinach, corn, and certain other vegetables, they qualify for DSHEA (pronounced as “de-shay”) treatment, and they are not regulated by the FDA under the types of strict standards that apply to drugs. However, because they have not undergone extensive testing in actual human clinical trials, lutein and zeaxanthin are prohibited by law from being labeled or advertised as having proven medical benefits. Under the DSHEA rules, the labels for lutein and/or zeaxanthin supplements are required by law to contain disclaimers such as, “These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”
Before 2002, commercially available “mixed carotenoid” products that claimed to contain zeaxanthin contained only very small (“trace”) quantities of zeaxanthin, and much higher concentrations of lutein. These lopsided ratios occur because, in nature, lutein is a much more dominant carotenoid, and is found in much greater quantities in most vegetables, and in other sources such as marigold flowers. As an illustration of the lopsided ratios, various sales brochures and other publications issued by the Kemin company (Des Moines, Iowa) for their FLORA-GLO™ brand of lutein from marigolds indicate that the ratio of lutein to zeaxanthin in their products are about 20:1 in favor of lutein.
However, in the early 1990's, various scientific findings began to suggest that the human retina (in particular, the macular portion of the retina, which is a yellow-pigmented spot at the center of the retina) appears to prefer zeaxanthin over lutein. This is evidenced by three factors: (i) the concentration of zeaxanthin is highest, and the concentration of lutein is lowest, near the very center of the macula; (ii) the fraction of lutein becomes higher, and the fraction of zeaxanthin decreases, around the outer portion of the macula; and, (iii) the macular portion of the retina apparently converts at least some of the lutein it receives into zeaxanthin (as noted below, it converts lutein into the S—R meso-zeaxanthin stereoisomer, which is not found in natural food sources). These factors are discussed in more detail in articles such as Bone et al 1985 and 1993.
One particular stereoisomer of zeaxanthin, referred to as the 3R,3′R isomer (or simply as the R—R isomer), is present in a number of food sources, including corn (“zea” is the Latin name for corn), and dark green vegetables such as spinach and kale. The R—R isomer became commercially available to the public only recently, starting in early 2002.
As described below, two other stereoisomers (known as the S—S isomer, and the S—R isomer which is also called meso-zeaxanthin) are also known, and the S—R isomer can be manufactured in commercial quantities, if desired, using lutein as a starting material. However, neither of those isomers are present in any significant quantity in any food sources, which raises questions over whether either of them can be sold to the public as dietary supplements under the DSHEA law, discussed above.
Despite its absence from food sources, the meso-zeaxanthin isomer is known to be present, in small quantities, in human retinas. Since it is not present in food sources, it is generally presumed and believed that meso-zeaxanthin, when found in the retina, is likely to be the result of enzymatic or possibly photo-activated chemical conversion of lutein into zeaxanthin.
If lutein, zeaxanthin, and other carotenoids (including β-carotene) are orally ingested in relatively high quantities, they compete against each other for uptake and transport through the intestinal walls and into circulating blood. This is presumed to be attributable to a carotenoid transport system, which can become saturated and unable to transport higher quantities of carotenoids through the intestinal walls and into the bloodstream. Therefore, if a mixture of zeaxanthin and lutein (or, presumably, zeaxanthin combined with β-carotene or any other carotenoid) is orally ingested, the presence of the lutein or other carotenoid will hinder and reduce the quantity of zeaxanthin which will reach and enter the circulating blood.
Because of certain apparent and presumed advantages of zeaxanthin over lutein, the first inventor herein has worked for more than a decade on the creation and commercialization of purified zeaxanthin (i.e., zeaxanthin which is free or essentially free of lutein, in a preparation that was not derived from a plant source). Among other things, he is the coinventor of five U.S. and numerous foreign patents on methods for making (and compositions containing) purified zeaxanthin, with little or no lutein present. Those US patents include two patents (U.S. Pat. Nos. 5,308,759 and 5,427,783) which relate primarily to pigmented feed additives for poultry and farm-raised salmon, as briefly mentioned above, and three subsequent patents which relate to using zeaxanthin for medical purposes, in humans. Those three patents which relate to medical use in humans are U.S. Pat. No. 5,854,015 (on a method of making the purified 3R,3′R stereoisomer of zeaxanthin), U.S. Pat. No. 5,747,544 (on a method of using 3R,3′R-zeaxanthin to treat macular degeneration), and U.S. Pat. No. 5,827,652 (on zeaxanthin formulations for human ingestion). The contents and teachings of all five of those patents are incorporated herein by reference, as though fully set forth herein. That inventor is the founder of ZeaVision LLC (St. Louis, Mo.; www.zeavision.com), which began actively selling purified zeaxanthin in April 2002.
Several years ago, that inventor realized he had a unique opportunity to test zeaxanthin as a potential agent for preventing or reducing sunburn. He was already serving as one of the volunteers in a small-scale trial to measure zeaxanthin concentrations in circulating blood and retinal tissue, as a function of daily dosage levels, and he was planning a vacation trip to the Caribbean. He was aware of the problems. (involving formation of canthaxanthin crystals in the retina) caused by the OROBRONZE product that had been pulled off the market some years earlier, and he realized that zeaxanthin probably would not cause similar problems, since it is naturally present in healthy retinas. Accordingly, he decided to begin taking a dosage of zeaxanthin (in the range of about 60 mg per day for roughly 2 weeks, increasing to about 80 mg/day for the week before the trip began) which began to cause a noticeable change in his skin color in a manner comparable to a mild suntan, just before leaving for his trip to the Caribbean.
During that trip, he noticed that he did not suffer any significant sunburns, even though he deliberately subjected himself to prolonged sessions of direct exposure to sunlight on a couple of occasions, at levels that would have caused serious sunburns during other times.
That trip provided the initial evidence showing that zeaxanthin, as a sole active agent and at a sufficient dosage which could begin to provoke a noticeable change in skin color, could serve as an effective way to prevent sunburn. However, the only supplies of purified zeaxanthin that were available at that time had come from lab-scale fermentation of the F. multivorum bacterial cells that are discussed below, in Example 1, and in the US patents cited above.
Subsequently, as soon as adequate supplies of purified zeaxanthin became available for testing on other people, the inventor mentioned above discussed his own experiences, in using high-dosage zeaxanthin to prevent sunburns, with certain other individuals. Two of those people decided to try it, and their successful and positive reports (described in Examples 2 and 3) confirmed that purified zeaxanthin, when taken at relatively high dosages, is highly effective in helping prevent and reduce the severity of sunburns.
Subsequently, three individuals carried out another set of skin protection tests, using a medical-grade ultraviolet lamp to determine their “minimal erythemal dosage” levels. The medical term “erythema” refers to the type of reddening of the skin that typically occurs during sunburn (similar types of erythema also occur during inflammation of an injured or infected area). Therefore, in the context of testing for sunburn protection, the phrase “minimal erythemal dosage” (abbreviated as MED) refers to a quantity of UV exposure that will generate a reddened surface appearance, of the type that occurs when skin is sunburned. MED values can be expressed in terms of minutes of exposure, if a single lamp is used for a series of tests, and if each volunteer ensures that the distance between the UV bulb, and his/her skin, is held constant throughout the entire series of tests (this can be done with the required degree of accuracy by steps such as leaning one hip against a wall while the other hip is being exposed, and placing the lamp base at a marked and unchanging location on the floor).
Control (or baseline) tests were carried out, before each test subject began taking high-dosage zeaxanthin, on an area of skin on or near the buttock region (or on the inside of the forearm, which did not have a substantial base tan since these tests were being done during winter months). Baseline MED values for a certain region of skin on a certain individual can be determined by using a UV lamp in conjunction with a shield of heavy paper or light cardboard, through which holes roughly 1 cm wide were cut. Masking tape was used in some of the tests to cover the holes, and a dark-blue opaque masking tape was used, which is normally used by painters and construction workers to avoid damaging the painted or veneer finishes of cabinets. This type of masking tape uses a mild and non-aggressive adhesive, and the choice of this type of tape minimized any risk that pulling the tape off of a small area of skin might irritate the skin or provoke or aggravate a reddening response. In other tests, instead of peeling away masking tape, a ruler or strip of cardboard was used to either cover or expose additional holes at appropriate times.
Regardless of which type of covering device was used in conjunction with a shield, a series of small areas of pale skin that had not previously been exposed to sunlight were given progressively increasing exposure times, usually in increments of 30 seconds if exposures up to 10 minutes were used, and in increments of 60 seconds if exposures longer than 10 minutes were used. When a series of exposures was completed, the person removed the shield and then waited for 8 to 24 hours, to give the erythemal reaction enough time to develop fully.
When that region of skin was examined under a clear bright light, the small areas of skin that were exposed to UV radiation for the shortest time periods did not have any noticeable reddening. However, the areas of skin that were exposed for progressively longer periods of time became progressively redder, darker, and more distinct, as the sequence of exposure durations increased. The test subject identified a specific small patch of skin which had both (i) noticeable reddening, with reasonably clear and distinct edges or margins, and (ii) the shortest UV exposure duration of any patches that had become reddened in that manner. The time period which corresponded to that particular patch of skin was recorded, as the MED dosage for that person in that test. These time periods, expressed in minutes or portions thereof, provided usable and reliable indicators of MED values, and they could be generated conveniently, without requiring complicated and expensive equipment to measure the exact levels of incident radiation.
After a baseline (or “pre-ingestion”) MED value was established for a test subject who had not been taking any zeaxanthin, that test subject then took a predetermined number of 10 mg capsules of zeaxanthin, each day, for a certain number of days. After that number of days, the person carried out a “post-ingestion” test, using the same sun lamp and the same procedures as used before, keeping all other factors constant.
In all of the people who participated in the UV lamp tests, at all dosage regimens tested (30 mg/day or higher), MED levels increased substantially. When the first inventor took 30 mg/day for 3 weeks, his MED increased from a baseline (pre-ingestion) level of 7.0 minutes, to a post-ingestion value of 10.5 minutes; when he then increased his dosage to 60 mg/day for another 3 weeks, his MED level increased even more, to 16 minutes. When the second inventor (who had previously taken 80 mg/day with no adverse effects) took 60 mg/day for 20 days, his pre-ingestion MED value of 5.0 increased to a post-ingestion value of 10. When a third volunteer took 50 mg/day for a single week, pre-ingestion MED value of 5.0 increased to a post-ingestion value of 7.3 (which was interpolated, since the skin area exposed for 7.0 minutes was nearly but not sufficient to qualify, while his 7.5 skin exposure appeared to be somewhat beyond a minimal qualifying level of redness).
These positive results, on three different test subjects who are all fairly large adult Caucasian males, consistently indicated that zeaxanthin dosages of 30 mg or greater did indeed decrease the vulnerability and susceptibility of skin to sunburning, and led to substantial increases in UV-exposure levels that were required to demonstrate any noticeable reddening of the skin.
It also should be noted that the first subject described above commenced taking high-dosage anti-oxidants, a number of weeks before his zeaxanthin regimen started. Therefore, any effect that those anti-oxidants may have had, in protecting his skin against UV damage, were factored into his baseline (pre-zeaxanthin) reading, and the increase in UV protection provided by the zeaxanthin regimen had to act on top of that.
Accordingly, one object of this invention is to disclose that zeaxanthin, when ingested at suitable dosages (such as about 5 mg/day for children, and 20 mg/day or greater in small and/or especially fair-skinned adults, and about 30 to 100 mg/day for a large adult), can provide highly effective protection against sunburns, even if no other tanning agents of any sort are used.
Another object of this invention is to disclose that zeaxanthin, when ingested at suitable dosages in a purified formulation where it is the sole or dominant carotenoid, can provide highly effective protection against sunburns.
A third object of this invention is to disclose that zeaxanthin, when ingested at suitable dosages over a span of several days, can provide effective protection against sunburns. A fourth object of this invention is to disclose that zeaxanthin can be added, as an active agent, to orally ingested tanning formulations that may contain any other desired active agent, and the zeaxanthin will increase the efficacy of the oral tanning agent, if it is present at a suitable dosage.
A fifth object of this invention is to disclose that zeaxanthin can be included as an active agent in orally ingested tanning formulations, and it will provide significant ocular benefits, with no known risk of retinopathy or other ocular damage (as can be caused by other carotenoids), even when ingested in large dosages.
Another object of this invention is to disclose that zeaxanthin, when ingested at suitable dosages, can help protect the skin of at least some patients who suffer from abnormally high vulnerability to sunlight, such as among patients who are taking certain types of antibiotics or other pharmaceuticals, or patients who are suffering from a disease or syndrome such as albinism or porphyria. 
Another object of this invention is to disclose that zeaxanthin, when ingested at suitable dosages, is likely to help reduce the incidence or severity of various types of unwanted skin discolorations or irregularities, such as skin blotching, splotching, or other irregular discolorations, and possibly the formation of severe and unwanted freckling and various other adverse conditions, in at least some patients.
These and other objects of the invention will become more apparent through the following summary and description.